Rose Byrne found it hard to be mean to A$AP Rocky in If I Had Legs I'd Kick You

Rose Byrne struggled to be mean to A$AP Rocky for scenes in If I Had Legs I'd Kick You because he was "so nice".

The 46-year-old actress stars as Linda in the comedy-drama film - which sees the mom juggle being a therapist while caring for her daughter, who is suffering from a severe eating disorder, and they are forced to relocate to a motel, run by James (Rocky), after their home was flooded.

Byrne praised the rapper, 37, in the new issue of Britain's HELLO! magazine, saying: "I knew Rocky's music and, obviously, he's in an extraordinarily high-profile relationship, but he's so talented. He couldn't have been sweeter. He worked very hard, and he has a supernatural charm.

"But my character had to be mean to him, which I found really hard because he was so nice."

Byrne joked how the cast and crew "were all waiting" for Rocky's 38-year-old partner, singer Rihanna, to accompany him on the set of If I Had Legs I'd Kick You.

As part of her preparatory work to play Linda - which she won a Best Actress Golden Globe gong for in January - Byrne met with moms whose children have special needs.

She explained: "It's fascinating to see the entire spectrum of those who cope and perhaps don't cope as well, and what that has done to their relationships - marriages, friendships, work life.

"It was an eye-opening experience, and it's forever changed my experiences of being a parent."

Byrne has had a new outlook on life and the jobs she takes as an actress since welcoming sons Rocco, nine, and Rafa, eight, into the world with her longtime partner, 55-year-old actor Bobby Cannavale - whom she refers to as her husband, but they are not married.

The Bridesmaids cast member explained: "Once you become a mother, it can't not inform each role you do. There's a before and after as a person; it's inherently there.

"All those experiences are, subconsciously or consciously, in your body, and you're going to have it in your nervous system."

Byrne thinks parenthood is tougher than being an actress.

Earlier this month, she told The Sunday People newspaper's Love Sunday magazine: "It's the hardest thing you'll ever do.

"The role of your life is to be a parent. And I'm married to an actor, so of course it's a constant push and pull of figuring it out and, 'What does my family need? Where is my career going?'"

And the Platonic alum is not afraid to ask fellow parents how they juggle a hectic work life with raising children.

Byrne said: "I think it's hard for any working parent. Honestly, I still ask people, 'How do you do it?'

"Both my sisters work really hard. They're raising kids, they're juggling stuff, and I feel lucky to have help. But it's constantly reassessing - like, 'What do they need? Where am I at?'"